有关钛酸锂材料的论文翻译~~论文翻译

1、Nanosized Li4Ti5Oi2/graphene hybrid materials with low polarizationfor high rate lithium ion batteries高倍率锂离子电池中低极化纳米钛酸锂/石墨混合材料的研究摘要We report a simple strategy to prepare a hybrid of lithium titanate （Li4Ti5O12, LTO）nanoparticles（纳米微粒）well-dispersed （很好地分散）on electrical conductive （传导的，导电的） graphene

2、nanosheets（纳米片）as an anode （阳极，正极，氧化极）material for high rate lithium ion batteries. Lithium ion（锂离子）transport is facilitated （使变得（更）容易，使便利）by making pure phase （纯相）Li4Ti5O12 particles （微粒，粒子）in a nanosize （纳米） to shorten the ion transport path. Electron transport （电子传输） is improved by forming a cond

3、uctive graphene network throughout （遍及）the insulating （绝缘）Li4Ti5O12 nanoparticles.The charge transfer resistance（电荷转移电阻）at the particle（粒子）/electrolyte（电解质）interface （界面）is reduced from 53.9Q to 36.2Q and the peak currents （峰值电流）measured by acyclic voltammogram （循环伏安法） are increased at each scan rat

4、e. The difference between charge and discharge plateau potentials （平台电位）becomes much smaller at all discharge rates because of lowered polarization （降低极化）.With 5 wt.% graphene, the hybrid materials deliver a specific capacity （容量）of 122 mAh g-1 even at a very high charge/discharge rate of 30 C and e

5、xhibit an excellent cycling performance,with thefirst discharge capacity of 132.2mAh g-1 and less than 6% discharge capacity loss over 300 cycles at 20 C. The outstanding electrochemical performance and acceptable initial columbic efficiency of the nano-Li4Ti5O12/graphene hybrid with 5 wt.% graphene

6、 make it a promising anode material for high rate lithium ion batteries. 2011 Elsevier B.V. All rights reserved.我们推出一个简单的方案，准备混合钛酸锂（Li4Ti5O12，LTO）纳米微粒均匀分散在导电的石墨纳米薄片 中，并使其作为一个高倍率的锂离子电池的正极材料。使用纯相钛酸锂粒子产生纳米尺寸粒子以缩短离子 传输路径，使锂离子传输更加便利。通过形成遍及绝缘钛酸锂纳米粒子的导电石墨网，以提高电子传输。 在粒子/电解质界面的电荷转移电阻从53.9Q减少到36.2Q，并通过循环伏安法测得

7、的峰值电流在每个扫描 速率下增加了。充电和放电平台电位之间的区别因为降低极化放电率变得更小。质量分数占5%的石墨， 即使在30 C的非常高的充放电速率下，混合材料能提供的122mAh g-1的具体容量，并表现出良好的循环性能。其中，首次放电容量为132.2 mAh g-1，并且在20 C和超过300次循环之后，放电容量损失小于6%。 纳米钛酸锂/含5%石墨的石墨混合物的优秀的电化学性能和可接受的初始库仑效率使其成为一种很有前 途的阳极高倍率锂离子电池材料。2011爱思唯尔B.V.保留所有权利。As one of the most important devices for energy sto

8、rage, lithium ion batteries （LIBs） have many outstanding properties, such as high energy density, long cycle life, fast charging and discharging ability and friendliness tothe environment. Therefore they have been widely usedas powersources for portable electric devices. Nowadays LIBs are also expec

9、ted to be a promising power source for electric vehicles （EV）, hybrid vehicles （HEV） and plug-in hybrid （PHEV） 1-4. To meet the dramatically increased demand for the emerging large-scale application of these EV, HEV and PHEV, electrode materials for LIBs with high safety, high power densityand long

10、cycle life are urgently required.作为最重要的能量储存设备之一，锂离子电池（LIBs）具有许多优异的性能，比如高能量密度，循环寿命 长，快速充电和放电能力和对环境无污染。因此，他们已被广泛用于便携式电子设备的电源。如今LIBS 预计也将是一种很有前途的电源，可应用于电动车（EV）,混合动力汽车（HEV）和插电式混合动力车 （PHEV）。现在，EV、HEV和PHEV新兴，并且大规模应用，为了满足这些急剧增加的需求，具有高安 全，高功率密度，循环寿命长的LIBS电极材料迫切需要。Among various anode materials for LIBs, spin

11、el lithium titanate（Li4Ti5O12, LTO） is considered an appealing candidate（一个有吸引力的候选人）with its fast Li+ insertion （嵌入）and de-insertion （脱出） ability, excellent cycle reversibility,high safety and zero-strain during charging and discharging5.Compared with carbon-based anode materials, such as graphite （

12、石墨），LTO exhibits a flatter operation potential plateau and higher operating voltage of about 1.55 V versus Li/Li+, which can make the issue of lithium dendrite deposition on the surface of anode materials entirely resolved 6.In addition, as the high equilibrium potential of the Ti4+/Ti3+ redox coupl

13、e （氧化还原对） is above the reduction potential （还原电位）of common electrolyte solvents （常见的电解质溶剂），a solid electrolyte interface （SEI）（固体电解质界面）film（膜）caused by solvent （溶剂）reduction does not form during the charge and discharge process.All of these merits （优点）make LTO more competitive as a safe anode materi

14、al for high power LIBs.However, as LTO is an insulator 7, the low electrical conductivity becomes a major drawback 缺点），which is unfavorable （不利的）to high rate capability 8,because the polarization （极化）of the electrode （电极） becomes serious when charged/discharged at a higher current density.In order t

15、o overcome the low electrical conductivity and further improve the power performance of LTO material, many approaches have been developed.As nanosized particles can reduce the lithium-ion diffusion path, particle size reduction or special nanostructural design is effective in improving its rate capa

16、bility .Until now, various wet-chemical methods have been developed and used for the production of pure-phase nanosized Li4Ti5O12 （n-LTO） particles, but agglomeration is usually inevitable during drying.Substituting （取代，代入，替代）theTi4+ or Li+ sites by an aliovalent metal is another important strategy

17、for conductivity improvement.This is expected to produce a high reversible capacity as well as maintain a high rate performance6,13,14.Preparing a hybrid of LTO with a conductive second phase, such as noble metal nanoparticles 15 or metal oxides 16 and conductive carbonaceous materials 8,17-21, is a

18、lso an effective way which has displayed significantly improved results.在各种各样的LIBS的正极材料中，尖晶石钛酸锂（Li4Ti5O12 , LTO）在其充电和放电中，具有快速锂 离子插入和去插入能力，良好的循环可逆性，高安全性和零应变能力，从而被认为是一个有吸引力的候选与碳基正极材料相比，如石墨，相对Li/Li+，LTO展示了平稳的操作潜在平台和约1.55 V的较高的操作 电压，它可以使正极材料表面锂枝晶沉积的问题完全解决。此外，高平衡电位的Ti4 +的/Ti3 +氧化还原对在上述常见的电解质的还原电位上，溶剂减少所造

19、成的固体 电解质界面（SEI）的膜并不在充电和放电过程中形成。所有这些优点使LTO作为高倍率LIB的安全负极材料更具有竞争力。然而，由于LTO是一种绝缘体，低电导率成为一个重大的缺点，这是不利于其高倍率性能的8，因为在 更高的电流密度充电/放电时电极的极化变得严重。为了克服低电导率，并进一步提高LTO材料的动力性能，已开发多种途径。由于纳米粒子可以降低锂离子的扩散路径，粒径减少或特殊的纳米结构设计能有效地改善其速率能力。直到现在，各种湿化学方法已开发，并应用于纯相纳米钛酸锂（LTO）粒子的生产，但集聚通常是在干燥过 程中的必然。由变价金属取代Ti4 +或Li+的位置是另一个重要的策。 预计这将

20、产生高的可逆容量，以及维持高利率的性能。准备用于导电第二阶段的LTO混合物，如稀有金属纳米粒子或金属氧化物和导电碳材料，也是一种有效 的方式，并且这已显示了显著改善的结果。Graphene, with an extraordinary electronic transport property,a flexible structure, high mechanical strength and high surface area for improved interfacial contact 22-24, is regarded as an ideal conductive additive

21、 to nanostructured hybrids as electrodes of LIBs25-30.In addition, graphene produced by the chemical reduction of graphene oxide has abundant functional groups on the surface, such as -COOH and -OH, and thus may provide a better connection with other materials to form a homogenous composite or hybri

22、d （复合或混合均匀）by interfacial interaction （界面相互作用）with some active particles （活性粒子）during preparation 25,27. In fact, the use of graphene to prepare hybrids cannot only increase electrical conductivity 23,29, but also improve the capacity and cyclic stability of anode materials28.Recently, Zhu et al. us

23、ed graphene as a conductive additive （添加剂） to fabricate graphene-embedded LTO nanofibers（制备石墨嵌入的 LTO 纤维）31, which showed great improved surface conductivity as well as rate capability.The graphene content was about 1 wt.% in the total carbon content of 7.2wt.%, which suggests that theaddition of onl

24、y a small amount of graphene could play an important role in the hybrid. However, it is worth noting that the amount of graphene added in the hybrid is not a matter of the more the better, as it can affect the initial columbic efficiency of the electrode materials, a key factor in the practical appl

25、ication of LIBs.With the increase of graphene content, the irreversible capacity loss in the first cycle increases, which may be attributed to the formation of a SEI film and the reaction of oxygen-containing functional groups （官能团） on graphene with lithium ions 32.Therefore, how to balance the two

26、effects of improving electrical conductivity and decreasing the initial efficiency that the graphene additive has on the LTO is another problem to be considered.In addition, in order to use the nanocomposite in large scale ,a facile （轻便）strategy for industrially effective production of the hybridmat

27、erial with well improved properties also urgently need to be developed.石墨，具有非凡的电子传输特性，灵活的结构，高机械强度和加大界面接触的高表面积。它被看作是对于 纳米结构混合物的一个理想导电添加剂，比如LIBs电极。此外，由石墨氧化物的化学还原剂产生石墨烯，在其表面具有丰富的官能团，如COOH和-OH，从而可以 制备过程中，与其他材料更好的接触，通过与一些活性粒子的界面相互作用，形成一个均匀复合物或混合 物。事实上，使用石墨制备混合物，不仅可以提高电导率，同时也提高了正极材料的容量和循环稳定性。 最近，朱等使用石墨作为导

28、电添加剂来制备石墨嵌入的LTO纤维，结果表明能很大提高表面导电率以及 其倍率性能。在7.2%总碳含量中，石墨含量仅约1%，这表明只有少量添加的石墨可以在混合物中发挥重要的作用。 然而，值得注意的是，在混合物中添加的石墨量并不是越多越好，因为它可以影响电极材料的首次库仑效 率，是LIBs实际应用的关键因素。随着石墨含量的增加，在第一个周期中的不可逆容量损失增加，这可能是由于形成的SEI膜和在石墨上含 氧官能团与锂离子的反应导致。因此，如何平衡石墨添加剂对LTO的两个效果，改善导电性和降低初始效率，是另一个要考虑的问题。 此外，为了在大规模使用纳米复合材料，具有良好性能的混合材料的工业有效生产也迫

29、切需要制定一个简 单实用的策略。In this work, we prepared a hybrid of n-LTO that was well-dispersed on graphene nanosheets as an anode material for LIBs.Graphene is chosen as a conductive additive to form a well connected conductive networkandreduce the difference between charge and discharge plateaupotentialsatall

30、 rates.It isfound that thehybrid material exhibits significantly improved rate capabilityand cycling performance. The relationship between initial columbic efficiency and graphene content in the hybrid is also taken into consideration.With 5 wt.% graphene content, the hybrid material shows outstandi

31、ng performance as an anode material in LIBs.在这项工作中，我们准备了很好地分散在石墨薄片上的n-LTO的混合物，它作为LIBs的正极材料。 石墨被选择作为导电添加剂，它能形成良好的可连接的导电网，减少在所有速率上充电和放电平台电位之 间的区别。结果发现，混合材料能显著改善速率性能和循环性能。首次库仑效率和混合物中石墨含量之间的关系也被 考虑其中。混合物中石墨含量为5%时，作为LIBs的正极材料有着出色的表现。2.实验2.1材料合成LTOwith 99.5% purityandabout2 p m average particle diameter （

32、粒径） was usedas the raw material.Forthe fabrication （制备） ofn-LTOparticles, ultrafine （超细）ball milling （磨）was carriedout for 1.5 h with alcohol as dispersant.A uniformly dispersed graphene （reduced from graphene oxide） solution using N-methyl-2-pyrrolidine （NMP） as dispersant was mixed with the n-LTO

33、material to give5 wt.% graphenein the hybrid,which was usedformost of the studyunlessotherwise mentioned,andsampleswithother amountsofgraphene were producedin the same way.After 1 h vigorous stirring, the mixture was heated at 200C to remove （移除） the solvent （溶剂）and ground in a mortar （研钵）.The sampl

34、e was then further heated to 500C and annealed for 4 h in an Ar atmosphere for healing thedefects （缺陷） of LTOduring ballmillingand for reduction （还原）of reduced graphene oxide.Finally, a grey powder of n-LTO/G hybrid was obtained.使用纯度为99.5%，平均粒径约2pm的LTO作为原料。n-LTO粒子的制备，用酒精作为分散剂，使用超细球磨1.5小时。均匀分散石墨（石墨氧化

35、物减少）解决 方案是使用分散剂N-甲基-2-毗咯烷（NMP），并与n-LTO材料混合，使混合物中石墨含量为5%，这是 在研究中最常用的方法，除非另有说明，并且其他不同量的石墨样品以同样的方式产生。剧烈搅拌1小时后，混合物加热到200。C，移除溶剂并盛放在一个研钵中。样本继续加热到500。C，在Ar气氛中退火4小时，为了弥补球磨过程中LTO的缺陷及避免减少的石墨 氧化物还原。最后，获得n-LTO/ G混合灰色粉末。2.2材料特性The structures of the n-LTO and n-LTO/G hybrid were characterized by scanningelectron

36、 microscopy （SEM, FEI Nova Nano 430） and transmission electron microscopy （Tecnai F20,200 kV）.Phase identification （相鉴别）was characterized by X-ray powder diffraction （衍射）measurements using a D/max 2400 with Cu Ka（1.54A） radiation,X-ray photoelectron spectroscopy measurements （Escalab 250, Al K a ） a

37、nd Raman spectroscopy （JY LabramHR 800） using 632.8 nm excitedlaser. The amount ofgraphene in the n-LTO/G hybrid was measured by thermogravimetry at a heating rate of 10C min-1 in air from 40 to 1000 by Netzsch-STA 449 C. 通过扫描电子显微镜（SEM, FEI Nova430纳米）和透射电子显微镜（Tecnai F20, 200千伏）对n-LTO 和n-LTO/ G混合物的结构

38、进行表征。通过X射线衍射测量，使用一个D /最大2400铜的Ka（1.54A）辐射，从而进行相鉴别。使用X射线光电子能谱测量仪（Escalab 250，铝Ka）和拉曼光谱仪（JY Labram HR 800），设定激发光 波长为632.8 nm。在n-LTO/ G混合物中的石墨量是通过热计量法计算，当供热率为10C min-1时，计算 Netzsch-STA 449 C下在空气中从40 C至1000 C时产生的热量。2.3电化学测量Thecharge-discharge properties of the samples were measured by assembling halfcell

39、s （单元，电解槽,电池）ina glove （密封） boxfilled with Ar gas.The working electrode was prepared as follows:first, active material（80wt.%）, acetylene black （10wt,%） and polyvinylidene（聚）fluoride binder （10wt,%）weremixed andground withNMP assolventto form auniform slurry,then coatedontoan aluminum foil （铝箔）and d

40、riedundervacuum at120C for 12h. After thefoil was cut into disks （13 mm in diameter （直径）and pressed, coin cells wereassembled with lithium metal as the counter electrode and a Celgard 2400 membrane as separator.The electrolyte was1 M LiPF6, ethylene carbonate:dimethyl carbonate = 1:1 in volumeratio.

41、Galvanostatic discharge-charge measurements （恒流充放电测量）were carried out under different currentdensities between 0.8 and 2.5 V （vs. Li/Li+）withacell test instrument（LANDElectronic Co., China） at room temperature.Cyclicvoltammograms （循环伏安法）were recorded from 0.8 V to2.5Vat different scanningrates using

42、 a Solartron 1287 electrochemical workstation, and the AC impedance spectrum（交流阻抗谱）wasmeasured by a Solatron1260ImpedanceAnalyzer （阻抗分析仪）inthe frequencyat 10 mV.rangefrom 10 mHz to 100kHzwith apotential perturbation （微扰）All the LIB active material.measurements mentioned abovearebased onthe total mass of the在充满氩气的密封盒里装配一半电池进行样品的充放电性能测试。制备工作电极方法如下：第一，活性物质（含量80%）,乙快黑（含量10 %）和聚偏二氟乙烯粘结剂（含 量10 %）混合，放入NMP中作为溶剂，使其形成均匀的浆料，然后涂到铝箔上，完成后在真空条件120C 下干燥12小时，等铝箔被切割成磁盘（直径13毫米